static IEnumerator <char> indicator_seq()
{
const string clock = "◐◓◑◒";
var clen = clock.Length;
var timer = new RealTimer(0.125);
var i = 0;
while (true)
{
yield return(clock[i]);
if (timer.TimePassed)
{
i = (i + 1) % clen;
timer.Restart();
}
}
}